Telephone system



Oct. 24, 1944. MOLNAR 2,361,314

TELEPHONE SYSTEM Filed April 1. 1943 a Sheets-Sheet 1 FINDER I co u gron F .CENTRAL OFFICE |oo 0.A.x. 2500 FINDER 4 CONNECTOR Two WAY TRK. C.AX. LINK 2540 I '4 TOLL RING oown TRK. cm. TOLL sw.:ao. 20: 270 7 4 TOLL RING DOWN TRK. cm.

. 2.60 DISTANT OFFICE '260 TOLL RING DOWN TRKCIR.

LOCAL sw.

TRAIN 460 cu. TRK. L k CIR. 410 r r A TX. T'RK CIR 400 COMMON STARTG LEVEL DIST.

- P03. P08 P05. P08. P08. DIST. DIST. DIST DIST. DIS'IT ODD TRK EVEN TRK. COMMON TRK GAX 8 OLR TX GROUP I GROUP GROUP TRKGROUP TRK. GROLP 02 "03 nol 04 L "05 1 IN V EN TOR. IMRE MOLNAR ATTORNEY Get. 24, 1944. MOLNAR 2,361,314

-TELEPHONE SYSTEM Filed April 1, 1943 6 Sheets-Sheet 2 2|80 22590 25|o-, I ANSWER CALL DELAYED FINDER SEL CALL sw. v sw. SEL.

OUTGOING TOLL SW. TRK. CIR. TRAIN s|oo 2soo- 2800 SEND. CONTROL sewn. FINDER 'sENucoNTRoL SEND. FINDER 2900i SEND. CONTROL SEND. Fl ND ER SEND.GONTROL SEND. FINDER REG SENDER REG. S'ENDER 50m TOLL SWITCHBOARD 1200 2530 TOSJ LiLfiLLJw DESK INVENTOR. IMRE MOLNAR ATTORNEY Oct. 24, 1944. l. MOLNAR 2,361,314

TELEPHONE SYSTEM Filed April 1, 1945 6 Sheets-Sheet '4 4 POSITION DISTRIBUTOR nol FOR common TRUNK GROUP Y 2023, uss w n45 mo 1 inss 2562 I A I95 202 m "NW 202: Y usxr- I A I v r 202 n20 -ua| 1 IST. 2ND. fiuazz ||4|- i "42 Il s "72 OVERFLOW 2 6|\L w 2 us u s I "'{iH l l W H? W54 If 20611 2563, I 5 25495 f POSITION msrmauron n02 I 2549 A roaooo TRUNK enoup r 20s? I '2022 7 POSITION DISTRIBUTOR n03 FOR even mumc GROUP OVERFLOW 2545 zse I 254s a I 254 '7,- POSITION DISTRIBUTOR n04 2606.7 3 FOR O.L.R.TRUNK GROUP fi ,2006

1 f 7 POSITION msrmau 0R no OVERFLOW 20663 20101 FOR 1'x mum: qnour aoss,

INVENTOR. mm: uoLuAR ATTORNEY Oct. 24, 1944. l. MOLNAR TELEPHONE SYSTEM Filed April 1, 1943 6 Sheets-Sheet 5 Q TO POSITION START RELAY I5IO INVENTOR. IMRE MOLNAR ATTORNEY rou.

INVENTOR.

ATTORNEY 6 Sheets-Sheet 6 ODD 8 COM.

IMRE MOLNAR w L 9 V T E 23 0 M .3 H2 53 MF wow v $0M m m 603 T Bow w F Bow w 80w 2 w 303 FIG.6

I. MOLNAR TELEPHONE SYSTEM P08. 7 START F'iled A ril 1, 1943 w JNBN CLASS OF SERVICE KEYS Keys at normal bring in cells of their class lesofH? GLR 4 oom mwom T 0 vmw I AU TO Oct. 24, 1944.

Patented Oct. 24, 1944 UNITED f STATES PATENT OFFICE 1 2,361,314 TELEPHONE SYSTEM Imre Molnar, Chicago, 111., asslgnor to Automatic Electric Laboratories, Inc., a corporation of Delaware Application April 1, 1943, Serial No. 481,413

25 Claims.

The present invention relates to telephone systems of the general character disclosed and claimed in United States Patent No. 2,167,710 issued August 1, 1 939, to Thomas F. Crocker and 'more particularly to a direct improvement over my copending application Serial No. 481,412, filed April 1, 1943.

General description completed directly or transferred to the TX position for completion. Thru calls, that is, calls in which the switchboard service is a tandem switching point, are handled at the toll positions in muchthe same manner as incoming calls. Outgoing calls in either local automatic or local manual exchanges and destined to be trunked over toll lines leading to other exchanges, are answered by the switching operators at the CLR or recording positions. The CLR operators make out the toll tickets for calls and may either complete the call directly or pass the ticket toa delay or TX operators position for completion. The TX operator later on sets up the connections from her position to both the calling and called parties.

It is customary also to arrange all if not most of the operators positions so as to be a universal position in which case the operator at such position may convert her position to either a toll, a CLR or a TX position.

In my copending application the various operators positions are universal in character and have keys for selectively conditioning such positions to receive a desired class of service such as toll, CLR or TX service.

In addition my copending application shows means ior simultaneously distributing incoming calls to the various operators positions which have been selectively conditioned to receive such classes of the incoming calls. For example, it

ing toll line group comprises a large group of trunks and the'total number of trunk lines to be answered at the operators positions is greater than the answering capacity at any one position,- the incoming toll trunk group has been divided into three groups (1) a common group,

(2) an even group, and (3) an odd group. The

CLR trunks, the TX trunk and the common toll trunks all terminate in all of the various operators positions. The odd group of toll trunks'terminates in only the first, third and each odd operator positions while tlie even toll trunk group terminates in the second, fourth, and each even operator positions. Each of these trunk groups is provided with an individual position distributor for distributing incoming trunk calls fromtheir respective trunk groups to operators positions which have. been selectively conditioned to receive such type of trunk calls bythe selective operation of the class of service keys provided at each of the operators positions.

Since there are three toll trunk groups such as common, odd and even there are three correwill be assumed that a certain number of operaof trunk calls.

The principal object or the present invention is to provide an overflow arrangement for permitting certain of the operators positions to act as overflow positions for the diflerent classes of incoming trunk calls at a time when theoperators positions normally assigned to take care or these classes of incoming trunk calls are not avail-.

able for use. For example, it will be assumed that certain of the-operators positions'have been assigned to take care of incoming trunk calls from only the CLR trunk group and that other positions are assigned to take care of incoming trunk calls from the CLR group only in case the normolly assigned operators positions are not available for handling an incoming CLR trunk call. In the particular case illustrated the CLR distributor would normally handle allof the incoming CLR calls providing any one of the operator's positions assigned to handle CLR service were idle.

The CLR distributor cyclically assigns the available CLR. positions in a predetermined order. At

a time when none of the normally assigned CLR with overflow keys for assigning the positions to act as overflow positions for the var.ous types of services such as CLR, toll and TX services.

The foregoing features together with others not specifically mentioned will be better understood from the following detailed description oi! the drawings.

Referring now to the accompanying drawings comprising Figs. 1 and la, and 2 to 7 inclusive, these drawings show by means of the usual circuit diagram 9. suflicient amount of apparatus in the toll switching system to enable the invention to be understood.

Figs. 1 and 1a show a trunking diagram illustratingthe local and toll trunking arrangements of a central ofliice exchange area. Figs. 1 and 1a are identicalin circuit diagram and reference characters to corresponding Figs. 1 and 1a in my previously mentioned copending application.

It will be possible therefore to refer to my copending application for any or the detailed circuits not shown in full in the remaining drawmgs of this application.

Fig. 2 discloses a distant office 200 having a toll switchboard 20I with ring-down toll trunks 'extending to this exchange area and in which these toll trunks are divided into three groups of trunks such as the common ring-down toll trunk 250, the odd ring-down toll trunk 260 and the even ring-down toll trunk 210. The CLR trunk circuit 410 illustrates a group of CLR trunks for handling calls from the local switch train 400 from local subscribers. The CLR trunk group and thetoll trunk group are shown as 1 terminating diagrammatically in the banks of the answer switch 2I80. The answer switch 2I00 and the call switch 2200 comprises one of the link circuits associated with the first operator's position. Full detail-circuits for the ring-down toll trunk 250, the TX trunk 400 and the answer and call switches 2I00 and 2300 may be secured from my copending application wherein similar apparatus and circuits have been given corresponding reference characters or numbers.

Fig. 3 dscloses in part the common start and level distributor 100 having reference characters similar to the common start and level distributor'100 shown in my copending application. Fig. 3 discloses only that part of the circuits which are necessary for a full understanding of the present invention.

Fig. 4 discloses flve position distributors IIOI, H02, H03, H04, and 05. The upper or common position distributor IIOI is shown in detail and It will be understood that the renialn'ng position distributors diagrammatically shown are similar in all respects to the upper position distributor. These position distributors are somewhat similar to the position distributors disclosed in my copending application with exceptions that each dlstnbutor is provided with additional relays to enable the operators positions to be utilized as overflow positions.

Fig. 6 discloses only part of the operators position circuit for position number 1.

Fig. '7 shows the class of service keys individual to operators position number 1. These keys comprise the CLR, the TX, and toll keys and the corresponding overflow keys for the corresponding classes of service.

Having previously described the drawings, a detailed description will now be given. It will now be assumed that the first four operators posit'ons in the toll switchboard I200 are normally assigned exclusively for use in answering incoming toll calls on toll trunks and therefore all of the class of service keys except the class of service keys corresponding to the class to be answered are operated in these four operators positions. For example, in operators position 1 the CLR key K2020, the TX key K2030, the overflow CLR key K2020, the overflow TX key K2030 and the overflow toll key K2040 are operated. Toll key K2040 is left in normal'position to enable this position to normally answer incoming calls from-both the common and the odd toll trunk groups. In response to opening the CLR key K2020 conductor. 2546 is separated from conductor 2545 thereby opening one of the circuits from the distributor to the CLR marking relay I240 at spring contacts I; at spring contacts 3 the conductor 205l is disconnected from conductor 2541 extending to the CLR distributor to thereby open one of the distributor start circuits for this position to the CLR distributor. At spring contacts 4 conductor 2065 is disconnected from conductor 2006 which extends to an individual distributor relay in the CLR distributor. At spring contacts 5 the CLR key grounds the conductor 2000 to busy this position in the CLR distributor and at spring contacts 6 the CLR call waiting lamp CW is discontact sprngs 8 the TX key K2030 separates I the conductor 20I4 from the TX call waiting lamp CW to thereby open the circuit to the TX call waiting lamp at this position. In response to the operation of the CLR overflow key K2020 contact springs I disconnects conductor 2540 from conductor 2545 thereby opening another circuit to the CLR marking relay I240, at contact springs 2 prepares a circuit for CLR overflow relay I210; at contact springs 3 disconnects conductor 205i from the overflow distributor start lead 2541', at contact springs 4 disconnects conductor 2005 from conductor 2000' extending to the overflow distributor relays. at spring contacts 5 grounds conductor 2000 for controlling the overflow CLR distributor relay to prevent CLR overflow calls being extended to this position,

' and at spring contacts 0 dsconnects the CLR call waiting lamp CW from the conductor 2001 to prevent the lighting oi this lamp at this position.

In response to the operation of the overflow key TX -key K2020, at spring contacts I opens another point in the circuit to the TX marking relay I250, at spring contacts 2 prepares a circuit for operating the TX overflow relay I280, at spring contacts 3 opens a point in the distributor start circuit to the overflow relays in the TX distributor, at spring contacts 6 grounds conductor 2066' to mark this position busy in the overflow section of the TX distributor, and at spring contacts 6 opens the circuit to the TX call waiting lamp CW.

In response to the operation of the overflow odd and common toll key K2040, at contact contact I2I3 and I228 over the distributor start conductor 2549 extending to the odd position distributor for energizing a distributor relay corresponding to the distributor relay H30 shown in springs I prepares a circuit for operating "the I overflow toll relay I260, at contacts 3 grounds conductor 2061' to prepare a circuit for the overflow relay H80, and at contact springs 4 opens the circuit to the toll call waiting lamp CW.

Since the toll key K2040 was not operated no circuit was therefore completed for the odd toll relay I2I0 at contact springs I and at contact springs 2 the conductor 2061 is grounded to pre- .pare a circuit for operating the distributor relay H40 in the common position distributor.

As soon as the operators'at these four positions talk key shown in the answer switch 2I80 and thence by way of conductor 2064 contacts I634- thru the winding of the slow-to-release relay position busy relay I640 to negative battery. A branch of this circuit extends from contacts I634 by way of conductor I5 to the winding .of relay I220 to negative battery.

Busy position relay I640, upon energizing, at contacts I641 disconnects ground from conductor 2065 thereby disconnecting ground from conductor 2061 extending to the position distributor by way of the toll key K2040.- At contacts I646 busy position relay I640 grounds conductor 205I to operate the' overflow CLR relay I210, the overflow 'IX relay I280 and the overflow toll relay I260, At contact I645 relay I 640 prepares a circuit for position start relay I5I0. The circuit for energizing the overflow TX relay I280 may be traced from the grounded conductor 205I thru contact springs 2 of the overflow TX key K2030 conductor I289 and thru the winding of overflow TX relay I280 to battery. The circuit for energizing the overflow CLR relay I210 may be traced from. the grounded conductor 205I thru contact springs 2 of the operated overflow CLR key K2020 conductor I219 and thru the winding of overflow CLR relay I210 to the negative battery. The circuit for energizing the overflow toll relay I 260 may be traced from grounded conductor 205I to the contact springs I of the overflow odd .and common toll key K2040, conductor 2068' and thru the winding of the overflow toll relay- I260 to battery. Relay I220 is operated in' response to the operation of talk key in the link and by ground extending over conductor 25I5 to prepare thru its uppermost sets of contacts various circuits to the marking relays I230, I240, and I250. At its lower contacts relay I220 prepares circuits extending to the distributor start leads of the various position distributors shown in Fig. 4. The operation of the overflow relays opens several circiuts extending to the marking relays while the overflow toll relay I260 opens several points in the circuit extending to the common and odd position distributor. At this time a circuit may be traced from grounded conductor 205I, contacts I2 and I229, distributor start the common position distributor.

Similar operations take place in the other three operator's positions in response to the operation of the CLR, and TX keys and the operation of the overflow CLR, TX and toll keys. In these three positions the overflow relays I280, I210 and I260 and the relays corresponding to relay I220 are operated to condition the circuits in the same manner as described for position 1. The distributor start conductor 202I is multipled to each of the operators positions and therefore any one of these operators positions having a talk key in one of their links operated will complete the circuit by way of conductor such as conductor 205i over contacts of a relay, similar to relay I220, to the common distributor start conductor 202I.

Relay H30, upon energizingfoverthe above traced circuit, at contacts H prepares a circuit for operating the toll marking relay I230, at contacts II3I opens the locking circuit of I I60 in case the latter relay is energized, at contacts H32 completes a locking circuit thru its upper winding by way of contacts HM and the winding of relay I I20 to grounded start conductor 202I, at contacts H33 prepares a circuit for relay H which at this time is not completed because of the operation of relay I640 which at contacts I641 has disconnected the ground from conductor 2065, and at contacts H34 opens a point in the circuit of relay H50. Relay H20 energizes in series-with the upper winding of relay H30 and at contacts H2I opens the origi-= nal energizing circuit of relay H30 but the latter relay is held in operated position over its upper winding in series with relay H20. It will be noted that only relay H30 is energized be-' cause in this case the first operator's position is ready to'receive an incoming toll trunk call. In case this first position was .not assigned to handle anin'coming toll call, then the toll key K2040 would have been operated and the conductor 2061 would have been grounded to complete a circuit for'the second distributor relay H40 by way of contacts H63 and H33. Assuming that this first position is assigned to handle incoming toll calls, and, at this time the. position busy relay I640 is in its deenergized position because she has no talking key in any of her links operated and therefore this position is not ready to'receive a trunk call, then under these conditions the conductor 2065 is grounded with result that the conductor 2061 is likewise grounded to complete the circuit for relay I I40. Q

In a manner similar to that just described the unnumbered conductors extending to the remaining-distributor relays may be grounded. Assum ng now that the first position is available for use and has a talk key and her position busy relay I 640 operated in readiness to receive an incoming trunk call, then only relays "H20 and H30 are operated.

It will now be assumed that an incoming toll trunk call has been extended from the distant oflice 200 by the toll switchboard 20l. In response to the extension of the toll ca l to ringdown toll trunk 250 the start relay 350 in this trunk circuit is operated in the manner described in my copending application. Start relay 300, upon energizing, at its contact completes a circuit for grounding conductor 2536 extending to the common start and level distributor 100 shown in Fig. 3. In response to grounding of conductor 2536, a circuit is completed by way of lockout contacts 101 and thru the winding of relay 160 to battery.

The operation of relay 160 causes another relay (not shown) to be operated in the common start and level distributor 100 to close contacts 825 and ground conductor 20I9 to thereby complete a circuit for lighting the toll call waiting lamp CW thru to the contact springs 4 of the odd and common toll key K2040. The operators at the various positions having their toll keys in normal positions are thus informed by the lighting of the toll call waiting lamp CW that a toll call is waiting to be answered. In addition a lockout relay (not shown) in the common start and level distributor 100 is operated, in response to the operation of relay 160, to open the original energizing circuit of relay 160 to prevent other incoming toll trunk calls from other subgroups of toll trunks from maintaining the relay I60 operated until this particular call and other simultaneous calls in this subgroup are answered. Conductor 2531 is grounded by the operation of relay 160 to prepare circuits to contacts on the marking relays for the purpose of marking the bank contacts in the answer switches associated with this operator's position to enable the answer switch to find the calling trunk line in accordance with the markings in its bank. Relay 160, upon energiz ng. at contacts 16I shunts the lockout contacts 101 to maintain relays 160 operated as long as conductor 2536 is grounded. At contacts 162 relay 160 grounds conductor 2562 to complete a circut for operating the toll marking relay I230 as follows: from the grounded conductor 2562 contacts III3, back contacts II1I, contacts H35, conductor 2023, contacts I2 and I223 and thru the upper winding of toll marking relay I230 to battery. At contacts I23I relay I230, grounds conductor 2535 to mark all of the toll trunks in the banks of the answer switch, at contacts I232 connects grounded conductor 2531 to conductor 2538 to mark the particular level in which this toll trunk terminates in the banks of the answer switch, and at contacts I234 grounds conductor 2011 to complete the energizing circuit for the position start relay I5I0 by way of contacts I646. It should be noted at this time that since only one of the position distributor relays, such as II30, is in energized position that only one of the toll marking relays is energized at one or the tour operators positions. Therefore the toll marking relay I230 at posltlon'l, in this case, is the only toll marking relay which is operated and therefore the toll trunk is only marked in the banks 01' the answer switches associatedwith this first operator's positions.

In response to the operation of the position start relay I5I0 conductor 2016 is grounded by way of contacts IOI2 to operate the start relay 2I60 in the answer switch 2I60. In response to the operation of the start relay 2I60 the answer switch is operated in the manner described In my copendlng application to find the incoming toll trunk which has been marked by the toll marking relay I230 and by the toll trunk in its banks. When the answer switch 2I00 finds this calling toll trunk the test relay 2I20 is operated to ground conductor 2016 at contact: 2I22 to complete a circuit thru the upper windings of relay I630 to battery. Relay I630 disconnects the grounded conductor 2064 from conductor 25I5 to cause the deenergization of relay I220 in Fig. 5 and to open the circuit of slow-to-release relay I640. In response to the answer switch 2I60 engaging with the calling trunk line, the start relay 350 in the ring-down toll trunk 250 deenergizes to disconnect ground from conductor 2536. Relays 350 and I220 deenergize before slow-to-release relay I640 deenergizes. In response to the removal of ground from conductor 2536 the circuit to relay is interrupted thereby causing the release of the latter relay. In addition the removal of ground from conductor 2636 likewise removes ground from conductor 2531 to thereby remove one of the markings in the banks of the answer switch. Relay 160 at contacts 162 disconnects ground from conductor 2562 thereby opening a point in the circuit to the toll marking relay I230. Relay I220, upon deenergizing, at contacts I223 opens another point in the energizing circuit of toll marking relay I230 and at contacts I229 removes ground from the distributor start conductor 202I in case none of the remaining three operators positions are available foruse at this time. Relay I230 deenergizes to disconnect the markings from the answer switch banks. In case the second operatorjs position is available for use the start conductor 202i will be maintained grounded with the result that relays H20 and II30 are maintained in operated positions until the slow-to-release relay I640 in position 1 deenergizes.

After an interval slow-to-release relay I646 deenergizes to disconnect ground from conductor 205I at contacts I646 and at contacts I641 grounds the mark busy conductor 2065 to thereby complete a circuit thru the toll key K2040 at spring contacts 2, conductor 2061, contacts H63 and H33, to the lower winding of relay II40. The second distributor relay II40 therefore is energized from grounded conductor 2065 in response to the deenergization of the slow-to-release relay I640 to cause the distributor to select the next operator's position which has been conditioned to receive incoming toll trunk calls. Relay II40, upon energizing, at contacts II45 prepares a circuit for controlling toll marking relay at the second operator's position, at contacts II4I opens the locking circuit of relay H36 to cause the latter relay to deenerglze, at contacts I'I42 completes a locking circuit for itsel! by way of contacts I I5I and the winding of relay H20, at contacts II43 opens a point in the circuit to relay H60, and at contacts II44 prepares a point in the circuit to relay H60. Relay II30 deenergizes and at contacts H35 opens a further point in the previously described circuit for the toll marking relay I230 at the position 1, at contacts II3I prepares a locking circuit for the last distributor relay H60, at contacts II33 opens the orignal energizing circuit of relay I I40 which is now locked energized in series with relay II26,

and at contacts I I34 prepares a point in a circuit in the next to last distributor relay H60. In case the second position is not in readiness to receive a trunk call the conductor corresponding to the conductor 2666 will be grounded to complete a circuit by way of the second position toll key and contacts H46 and N36 for the lower winding of relay II60. The relay H60, under these conditions. would be operated to lock itself in series with relay H26 and to cause the deenerglzatlon otrelay H60 in the same manner 2065 is grounded to complete a circuit by way of contacts 64 and H54 and thru, the lower winding of distributor relay 1 I30 to battery. This latter relay at contacts ISI opens a locking circuit of the last distributor relay H60 and locks itself in the same manner as previously described.- From the foregoing description it will be seen that the distributor relays are cyclically operated in accordance with whether or not the assigned operators positions are available for use. It-can also be seen that when the position busy relay I640 is in deenergized position that .this corresponding positionis marked busy or unavailable. for use. These positions are rendered idle and available for use when busy position relay I640 is in energized position and when the conductor 25I5 is grounded and the corresponding relay I220 is operated.

Returning now to the time when an answer switch in the first operator's position has found and connected with the incoming toll trunk call, it should'be mentioned that the relay I60 is deenergized, in case no other trunk calls have been made in this particular subgroup, to remove ground from conductor 2562, and to cause the removal of ground from conductor 20I0 to extinguish toll call waiting lamps CW at these four operators positions.

The foregoing operations just described are fully disclosed in my previously mentioned copending application and have been described .herein'to enable the invention to be more clearly understood. For the purpose of describing this invention it will beassumed that the operators positions which have been selectively conditioned to answer incoming toll calls are busy or unavailable for use. Under these conditions none of the relays corresponding to relay I220 will be in operated'position with the result that the distributor start lead 202I is not grounded and therefore relay H20 and none of the distributor relays are in operated position. It will be further assumed that another position has been selectively conditioned by the operation of all f the class of service keys except the overflow class of service key K2040 for the odd and common toll service. Since the key K2040 is not operated,

- the overflow toll relay I260 in Fig. 5 is likewise not operated. Now when this first overflow position operated a talk'key in one of her links; the corresponding position busy relay, corresponding to relay I640, and the relay, corresponding to relay I220, in her position are operated in the same manner as described for the vilrst position. ,In order to clearly describe the operation of this operator's position when as- Now therefore, when the overflow operator operates one or her talkkeys in one of her links the relay I220 is operated and conductor 205I- is grounded to complete" a circuit for grounding the distributor start conductors 2549* and 202I' ex-,-

tending respectively to the overflow distributor I means in the common and odd position distributors HM and II 02 respectively. Acircuit may now be traced for energizing the overflow relay II10 from from grounded conductor 205i by way of contacts I264 and I229, conductor 202I contacts] I 22 of relay II20, which is now in the deenergized position because the distributor start conductor 202'I is not groundechand thru thewinding of ove rflow relay H10 to battery. A similar. relay inthe odd position distributor is energized from grounded conductor 205i byway of contacts I263 and I228 and conductor 2549' extending to the odd distributor overflow relay corresponding to relay III0. Relay H10, upon energizing, at bank contacts II'II opens the-circuit extending to the marking relays at the operator's positions which are normally assigned to answer toll calls and at front contacts at H prepares a circuit for energizing the series relay I I95 in series with the toll marking relay of the first operator's position which has been conditioned to act as an overflow toll position. At contacts H12 relay II'I0 prepares locking cirfcuits for the overflow relays H80 and H90. At

signed for overflow service, itwill be assumed that-drawings shown in Figs.'5, 6, and '7 are the drawings of this overflow position. Under these conditions the odd toll relay |2I0 is prepared contacts II 13 relay I-I'I0 cornpletes a circuit forposition is unavailable for use or not conditioned to receive incoming toll trunk calls. lit-contacts H14, relay III0 completes a circuit forthe second overflow relay II00-if the second overflow position is not-available'for use or not' conditioned to receive incoming toll trunk calls. In case additional positions are to act as overflow positions then additional H and I I90, would be provided for such positions and these relays would operate in the same manner as described for relays II 80 and 1 I90.

In case the first overflow position is assigned to answer incoming toll calls and has been marked available for use by the throwing of the talk key in any one of thelinks at her position, then ground is removed from conductor 2065- and contacts me only first overflow relay II80 instead of operating the same.

Assuming now that a st relay 350 in Fig. 2 is operated to ground conductor 2536 then relay operates as previously described and conductor 2531 is grounded. Contacts 625 are also closed to ground conductor 20I9 to light the toll call waiting lamp CW at the operators positions. At contacts 162 relay 160 grounds conductor 2.562 to complete a circuit for relays I I 05 and toll marking relay I230 as follows: ground by way of armature I62, conductor 2562-, contacts III3, front contacts II1I, winding of relay 95, back contacts II 6|, con- .ductor 2023', contacts I26I and I223 and thru the upper winding of toll marking relay I230 to battery. Relay 05 at contacts 'II96 completes a circuit for maintaining relay H10 energized thru its lower winding and likewise prepares a locking circuit for the upper windings of the *flzst and second overflow relays H00 and H90. Toll marking relay I 230, upon energizing, at con tact I2 3I grounds conductor 2535 to markthis groupof toll trunks as calling in the'bank accessible-'to answer switch 2!. At contacts I232 art relay such as start in the same manner as previously described.v

relays, such as relays.

prepares a circuit for the to conductor 2000 to mark the level of bank contacts in which the calling trunk line termiposition. At contacts I204 toll marking relay I200 grounds conductor 2011 to complete a circuit for energizing the position start relay IOI0. Position start relay IOI0. upon energizing. at contact IOI2 grounds conductor 2010 to energize the start relay 2I00 in the answer switch having its talk key operated to cause this particular answer switch to hunt and flnd the calling toll trunk line in its banks. The calling trunk line is individually marked in one section of its banks by operation of the relays in the ring-down toll trunk 200 while the other sections of the answer switch banks are marked by the operation of the toil marking relay I200. When the calling trunk line is found test relay 2I20 operates to ground conductor 2010 to operate relay I000 ground is removed from conductor 20I0 extending to relay I220, and ground is disconnected from the position busy relay I040 to cause the deenergization of these two relays. Relay I040 being a slowto-release relay deenergizes an interval after relay I220 deenergizes. In response to the deenergization of relay I220 the previously traced circuit for energizing relays H and I230 are interrupted at contact I223 with the result that relays H00 and I200 now deenerglze. In case the second overflow position is available for use then ground will be maintained on the overflow start conductor 202I' with the result that relay H10 will be maintained energized from the second overflow position when the original energizing circuit from the first overflow position is opened at contact I220. It is necessary that relay H00 deenerglze and permit the deenergization of relay H10 in case one of the previously mentioned operators positions, which have been normally assigned to take care of incoming toll lines, has become idle in the meantime. In this case one of thedistributor relays H00 to H00 inclusive will be operated in series with the common distributor busy relay H in the manner previously described. Relay H20 at contacts H22 opens the circuit extending thru the upper winding Of overflow relay H10 so that relay H10 at this time may be deenergized to permit the operators positions, normally assigned to handle such calls, to be selected for use in place of the overflow positions. However, assuming that these normally assigned operators positions are still busy and unavailable. a circuit will be completed for the first overflow relay H00 when the slow-to-release relay I040 flnally deenergizes. This circuit may be traced from ground by way oi contacts I041, conductor 2000, thru the overflow toll key contacts 2 of key K2040. conductor 2001', contacts H10 and thru the lower winding of the flrst overflow relay H00'to the battery. Relay H00 at bank contacts HOI opens the previously traced circulit for toll marking relay I200 and at front contacts II'0I prepares a circuit by way of back contact HOI for operating the-toil marking relay in the second overflow position corresponding to toll marking relay I200. At contacts H02 relay H00prepares-a locking circuit for its upper winding. Assuming that the second overflow position is available for use and ready to receive an incoming trunk call. its relay.

corresponding to relay I220, Is operated and has grounded conductor 202i tomaintain relay H10 in operated position dependent upon the operated condition of contacts H22 of the busy relay nates in the bank of the answer switches in this relay I200 connects the grounded conductor 2001 H20. Now a second call from an incoming toll trunk in the common group will ground conductor 2500 to operate relay 100. or maintain it operated in case it is in the same subgroup.

Conductor 2002 is grounded to complete the circuit for energizing relay H00, this time in series with the toll criarking relay in the second overflow positiomcorresponding to relay I200. Relay H00 again operates and at contacts H00 maintains the overflow relay H10 operated to prevent interference should a normally assigned operator's position become available for use at this time. Contact H00 also completes the locking circuit by way of contact H12 for the upper I winding of relay H00. The position start relay in the second overflow position is then operated to cause its associated answer switch at that position to find the second incoming trunk call as marked by the toll marking relay in the second overflow position. After this trunk call is found the relay, corresponding to relay I220, is deenerglzed to open the circuit of the toll marking relay at the second overflow position and the circuit of relay H00 to cause the deenergization of these relays.

In the above description, it was assumed that the second incoming toll call occurred before the operator at the flrst overflow position had completed the first toll call to the desired called destination and therefore before the operator at the flrst-overflow position had operated another talk key in an idle link at her position. However, if the second incoming toll call occurred after the first overflow position was ready to receive another toll call on another link in her position, then the second incoming toll call would be again routed to the first overflow position because the overflow positions are always selected in a predetermined order. That is, an overflow call is always routed to the first overflow position if it is idle and available for use and subsequent overflow calls are only routed to a second overflow position in case the flrst overflow position is busy and unavailable for use. This overflow distribution is different from the normal distribution of incoming toll calls to the operators positions normally assigned to handle such toll calls because the normally assigned positions are taken into use, if idle, in a cyclically operable chain as long as any one of the normally assigned positions are available.

As soon as any one of the normally assigned operator's positions, such as the first four operator's positions previously mentioned, has operated a talk key at her position thereby marking it idle and available for use, the relay corresponding to relay I220 at such position is operated to ground conductor 2 02Ifrom grounded conductor 200! as previously described. In response to the grounding of conductor 202i at any one ofthe positions-relays H20 and H00 are operated. Relay H20 at contacts H22 opens the circuit to the upper winding of overflow relay H10 to prevent the energization of such relay. In case relays H10 and H00 are both operated at this time, then ground at contacts H00 prevents the'release of relay H10 until the overflow position has answered the call which was routed to this overflow relay H10 opens a point the circuit to relay H and to the toll marking relays at the overflow positions. At back contacts HII relay H prepares the circuits to the toll marking relays,

such as relay I230, of the normallyassigned operator's positions which have been selectively conditioned to normally answer incoming toll calls.

In the odd position distributor the relays, corresponding todistributor busy relay H and distributor relay I I30, are operated in case the first normally assigned operator's position is marked idle and is selectable for use. Its relay I220 is III operated and grounded conductor 205I completes circuits for these distributor relays over contacts I2I3 nd I228 and distributor start conductor 2549. Assuming now that there is an incoming toll trunk call in the odd toll trunk group 260 in which case the start relay in the odd ring-down toll trunk 260 grounds conductor 268 to energize relay I over contacts I03 and to ground con-- ductor 2539. Relay I30, upon energizing, at contacts 132 grounds conductor 2563 and causes a relay (not shown) to' close contacts 635 to ground conductor 20I9 to light the toll call waiting lamp CW. Relay'130 also causes thelockout relay (not shown) in the common start and level distributor 100 to open contacts I03 to prevent other incoming toll calls in other subgroups of the odd group from interfering with the operations of relay 130. At contacts I3I relay I30 maintains its own operating circuit and conductor 253$ grounded as long as conductor 260 is grounded.

When conductor 2563 is grounded a' circuit may be traced thru the operated distributor relay, corresponding to relay I I30, for grounding conductor 2534 to complete a circuit for the toll marking relay I230 by way of contacts I2I2 and I224. Re-

lay I230, upon operation, operates contacts I23I and I233 to mark thetoll trunk group and level of bank contacts accessible to the answer switch and operates the position start relay I5I0, in the same manner as previously described, to cause the answer switch to flnd the odd calling trunk Lne. When the trunk line is found by the answer switch, ground is removed from the conductor 26B and the answer switch test relay 2I20 causes the operation of relay I630 as previously described. Relay I630 causes the release of relay I220 and after a predetermined interval, the slowto-release relay I640 deenergizes to ground conductor 2061 to operate thesecond distributor relay such as H40 in both the'common and odd position distributors HM and I I02. The operation of the distributor relays such as I I40 in both distributors causes the deenergization of relay I I30 while maintaining the distributor busy re-' lay H20 energized. Relay I220,'upon releasing,

opens circuits to the toll marking relay I230 and removes ground from the distributor start conductors 202I and 2549 only in case no other norinally assigned operators positions are marked idle and selectable for use. Relay 130 deenergizes and removes ground from conductor 2539 and. causes" the disconnection of ground from conductor -20I9 to extinguish the toll callwaiting lamp CW. In case the second normally assigned as any one of these positions are marked idle and available for use.

The overflow relays in the common and odd distributor are only used when none of the normally assigned erators positions are available for use. Under these circumstances the distributor busy relays such as relay H20 are no longer operated and therefore at contacts such as contacts H22 completes circuits for the overflow relays such as relay H10 when any one of the positions assigned to act as overflow positions are marked idle and available for use. The overflow position relays such as relays H60 and H are operated to prepare the circuits to the toll marking relays in the same manner as previously described. If one of the normally assigned 0perators positions should again be marked idle and selectable for use before another incoming toll call is received, then relays such as relay H20 will be operated in serieswith one of the tributor isin use on a call the relays such as relay H maintains the relays such as relay 6 H10 operated thru their lower windings to prevent the stealing of this call from the overflow position and then when relay H95 deenergizes after the overflow position answer switch has found this call, the relays such as relay H10 are deenergized to disconnect the overflow relays ofthe distributor and to permit the regular distributor relays to function and handle the incoming toll calls.

Having described the first operator's position as being used as a regularly assigned position for answering incoming toll calls and then used as an overflow position for answering incoming toll calls when all the regularly assigned positions are busy or available, a brief description will now be given of the use of this position as a CLR position for answering only CLR trunk calls. In this case all of the keys except the CLR key K2020'are operated. The overflow position re- .lays I280, I210 and I260 are operated in response to the operation to the corresponding overflow keys to prevent the use of this position as an overflow position. -The operation of the TX key K2030 busies this position to incoming TX calls and the operation of the toll key K2040 likewise busies this position to incoming toll calls from the common and odd incomin toll trunk groups by controlling the distributor relays in their respective position distributors to pass over this position when selecting their next marked, idle position for use on such class of calls-in the manner previously described.

As long as this position is unavailable for use conductor 2065 will be grounded to complete a circuit by way of the CLR key spring contacts 4' for grounding conductor 2006 to prepare or operate the CLR distributor relay, corresponding to relay I I40, to prevent the CLR distributor from selecting this position. In order to render this position available for use the operator will operate one of the talk keys in one of her idle links.

Assuming that the talk key in the answer switch 2I80 is the key operated thentlie operation of this key operates relays I640 and I220'as previously described. Relay I640 at contacts I641 disconnects ground from conductor 2065 to thereby dlsconnect ground from conductor 2006 extending from the CLR key to the CLR distributor. At contacts I646 relay I640 grounds conductor 205I to operate the odd toll relay I2I0 .2546 and 202i.

'toll relay I260 at contacts I263 and I264 prevents grounding of the overflow distributor start leads 2649 and 202I when conductor 205i is byi' way of the toll key contact springs I and conductor 2060, and at contacts I645 prepares a circuit for the position start relay II0.

Relay I2I0, upon energizing, at contacts I2 and I2I2 opens points in the circuit to the toll marking relay I230 to prevent its operation. At contacts I2I3 and I2I4 relay I2I0 opens circuits to prevent grounding of the distributor start leads The operation of the overflow grounded and at contacts I26I and I262 opens further. circuits to the toll marking relay I230. At contacts I21I the CLR. overflow relay I210 opens one of the circuits to the CLR marking relay I240. At contacts I2BI the overflow TX relay I280 opens one of the circuits to the TX marking relay I250 while the other circuit for the TX marking relay I250 is opened at the contacts spring I of the TX key K2030. Therefore at the time relay I220 is operated there is only one circuit remaining for operation of a position marking relay and this circuit extends from the CLR marking relay I240 over contacts I222, conductor 2546 to spring contacts I of the CLR key K2020 to conductor 2545 which extends to the CLR position distributor where it terminates in the contacts corresponding to contacts H35. In a similar manner only one other of the operated contacts of relay I220 is now effective for grounding one of the distributor start leads. This is distributor start lead 2548 extending to the CLR distributor to cause the op--- eration of the distributor busy relay and the first distributor relay corresponding to relays I I20 and H30. This circuit may be traced from grounded conductor 205i, spring contacts 3 of the CLR key K2020 to conductor 2541, over contacts I226 to the CLR distributor start lead 2646. The circuits for grounding the distributor start leads 2548', 2010'and 2010 are opened at the operated keys at contacts springs 3 at the opcrators position and the circuits to the distributor start leads 2548, 2546', 202i and 202I are opened by the operation of relays I280 and I2I0,

When a local subscriber such as TI operates the local switch train 460 to seize a CLR trunk, such as 410, a start relay in this trunk circuit is operated to ground conductor 2530 to complete a circuit by way of contacts 1| I for operating relay 150 and grounding conductor 253i for marking purposes. Relay 150 at contacts I locks itself to ground conductor 2530 and at contacts 152 grounds vconductor 256I. Relay 150 causes the operation of a relay (not shown) \to operate contacts 055 to ground conductor 2001 to thereby light the CLR call waiting lamp CW. A lockout relay (not shown) in the common start and level distributor I00 alsooperates contacts II I to prevent a CLR trunk call in another subgroup from interfering with this trunk call. When relay 150 grounds conductor 256i a circuit is completed thru the CLR position distributor operating the CLR marking relay I240. This circuit extends from grounded conductor 256i thru back contacts of the CLR overflow relay, similar to contacts II", to operated contaets on the operated CLR distributor 'relay, similar to contacts II35, to conductor-2545 and thence by way of contact springs I of the CLR key K2020 to'conductor 2546. contacts I222, and then thru the upper winding of CLR marking relay I240 to battery. Relay I240 at contacts I24I grounds conductor 2523 to mark the CLR trunk group in the banks of the answer switch associated with this position, at contact I242 connects grounded conductor 253i to conductor 2538 to mark the level in the banks of the answer switch in which this trunk line terminates, and at contacts I243 completes the circuit for operating the position start relay I5I0 over conductor 2011 and contacts I645. Relay I5I0 operates the start relay 2I60 to cause the answer switch to find the marked CLR trunk line whereupon the test relay 2I20 operates to cause the operation of relay I630 and the release of the CLR start relay in the CLR trunk circuit to disconnect ground from conductor 2530 in case no other CLR trunk in this subgroup is calling. Relays I220 and I240 deenergize in response to the operation of relay I630 and after an interval relay I640 deenergizes to advance the CLR distributor in the same manner as described for the toll common position distributor. When ground is disconnected from conductor 2530 relay 150 releases and ground is disconnected from the conductor 253i. Relay 150 also disconnects ground from conductor 256i and causes ground to be disconnected from conductor 2001 to extinguish the CLR call waiting lamp CW. The lockout contacts 1 I I are likewise closed to again prepare the original energizing circuit of relay 150. A subsequent call from a CLR trunk line is routed by the CLR distributor to the next marked idle one of the operator's positions which has been selectively conditioned by the class of service keys to answer incoming CLR trunk calls.

Having described how the first operator position may be used as a regularly assigned position for answering incoming CLR trunk calls.it will be assumed that this position is assigned to act as an overflow position to answer only incoming CLR trunk calls. In this case all of the keys except the overflow CLR key K2020 are operated and therefore relays I280 and I260 are operated and relays I2I0 and I220 will be operated when this position is marked idle and available for use by the operation of one of the talk keys in an idle link. In this case the only remaining circuit which may now be completed for a marking relay is the CLR marking relay I240, and this circuit'may be completed over contacts I2II since the overflow CLR relay is not operated. All other circuits for marking relays are opened at the keys or by the operation of the relays I260 or I2I0 in the manner previously described.

This overflow position is never taken into use unless all of the normally assigned CLR positions are unavailable at which time the CLR busy .distributor relay corresponding to relay II20 will be deenergized. When this CLR busy position relay is deenergized and an overflow position is marked idle and available for use the CLR overflow distributor start lead 2540' is grounded by the operation of relay I220 to operate the CLR overflow relay corresponding to relay II10. If an incoming trunk call is received at this time a circuit may be traced for the CLR marking relay I240 as follows: from grounded conductor 256i thru operated contactson the CLR overflow relay, corresponding to contacts II'II winding of the overflow series relay, corresponding to relay H35, back contacts on the first overflow'distributor relay (if the' flrst position is marked idle) and thence over conductor 2545' thru contacts springs I of K2020 and over conductor 2546', contacts I2II and I222-and thruthe upper winding of CLR marking relay I240 tn battery. In the same manner as previously described the CLR marking relay I240 marks the calling CLR trunk call in tlie banks of the answer switch in this position and operates the position start relay ISIS to cause the preselected answer switch to operate and find this calling trunk line. Since the re-.- maining'operations are the same as previously described for the'overflow circuits of the common position distributor no further description will be given other than to state that as soon as one of the regularly assigned positions become available for use, the CLR trunk calls are then routed to such positions instead of the overflow positions.

In a similar manner any one of the operators positions may be selectively conditioned by the operation of the proper class of service keys to answer only the TX trunk calls or may be conditioned to act as an overflow position for the TX calls. A description of the operation of the position for use on TX calls is believed unnecessary as it is substantially the same as that described for CLR calls. In addition there is no reason why any one or more of the positions may not be used to answer all or only a limited number of the services. CLR, and TX, or toll and CLR, or CLR and TX, or only one service. Also any one or more positions could be condtioned to act as overflow positions for all such services or only a'limited number. In cases where a position is simultaneously takingpare of two or more services andif such a position should simultaneously receive incom'ng calls from two different classes of trunks then the call which would be answered at this position would be the trunk line which terminates in the lowermost bank' level of the answer switch while the second of the calls would later on be answered by another operator's positions.

Having described the invention and what is consideredto be new and patentable "s set forth in the following claims.

corresponding overflow key for each of sa d trunk groups at each of said positions, means inc ud ng said class of service keys at certain of said operators pos'tions for selectively conditioning said certain positions to receive incoming trunk calls from only said first trunk group, means including said class of service keys at other of said operators positions for selectively condition ng sa'd other positions to receive incoming trunk calls from only said second trunk group. means including said overflow keys at predetermined ones of said operators posit'ons forselectively conditioning said predetermined positions to receive incoming trunk calls from both said first and second trunk groups, and means for routing incoming trunk calls from said first trunk group to said predetermined postions only in case none of said certain operators positions are idle and selectable for use and for routing incoming trunk calls from'said second trunk group to said predetermined positions only in case none of said other operators positions are idle'and selectable for use. I

2. In a telephonesystem, a first group of trunk lines of one class, a second group of trunk lines of a different class, a plurality of operators positions, means for marking each of said positions That is a position may answer toll.

idle and selectable for us only when the operators at such positions are ready to receive an incoming trunk'call, a class of service key for each of said trunk groups at each of said positions, a corresponding overflow key for eachof said trunk groups at each of said positions, means including said class of service keys at certain of said operators positions for selectively conditioning said certain positions to receive incoming trunk calls from only said first trunk group, means including said class of service keys at other of said operators positions for selectively conditioning said other positions to receive incoming trunk calls from only said second trunk group, means including said overflow keys at certain predetermined ones of said operators positions for selectively conditioning said certain predetermined positions to receive incoming trunk calls from only said first trunk group, means including sad overflow keys at other predetermined ones of said operators positions for selectively conditioning said other predeterm ned positions to receive incoming trunk calls from only said second trunk group, means for routing incoming trunk calls from sad first trunk-group to said certain predetermined operators positions only in case none of said certainoperators positions are idle and selectable for use, and means for routing incoming trunk calls from said second trunk group to said other predetermined operators positions only in case none of sa d other operators positions are idle and selectable for use.

3. In a telephone system, a first group of trunk lines of one class, a second group of trunk lines of a different class, a puralitr of operators positions, means for marking each of said positions idle and selectable for use only when the operators at such positions are ready to receve anv incoming trunk call, a class ofservice key for each of said trunk groups at each of said operators positions, a corresponding overflow key for each of sa d trunk groups at each of said operators positions, means including said class of service keys at certain of sa d operators positions for selectively conditioning said certain operators positions to receive incoming trunk calls from only said first trunk groups, means including said corresponding overflow keys at other of said opeiators postions for selectively conditioning said 0 her operators positions to receive incoming trunk calls from only said flrst trunk group, and means for routing incoming trunk calls from said first trunk group to said other operators" positions only in case none of said certain operators posi, tions are'idle and selectable for use.

4; In a telephone system, a group of incoming toll trunk lines, a plurality. of operators positions, means for marking each of said operatorspositions idle and selectable for use only when the operators at such positions are ready to receive an incoming trunk call, a class of service key corresponding to said trunk group at each of said operators positions, a correspondingoverflow key corresponding to said trunk group at each of said operators positions, means including said class of service keys at certain of said operators positions for selectively conditioning said certain operators positions to receive incoming trunk calls from said trunkgroup, means ineluding said corresponding overflow keys at other of said operators positions for selectivelyc'onditioning said other operators positions to receive incoming trunk calls from said trunk group, and means for routing incoming trunk calls from said trunk group to said other operators positions tain operators positions only in case none or said certain operators positions are idle and selectable for use.

5. In a telephone system, a group oiincoming toll trunk lines, a plurality of operators positions means for marking each of said operators positions idle and selectable for use only when the operators at such positions are ready to receive an incoming trunk call, means for selectively tional means in said distributor for selecting only a marked one of said other operators positions in accordance with said diiierent selective conditioning means, and said operators positions are marked idle and selectable ior use.

6. In a telephone system, a plurality of groups of incoming trunk lines, a plurality of operators positions, means for marking each of said operatorspositions idle and selectable for use only when the operators at such positions are ready to receive an incoming trunk call, selective means in each of'said positions rendering said positions capable of answerin a trunk call from any or said trunk line grou overflow selective means in each or said positions rendering said positions capable of answering a trunk call from any of said trunk line groups, and means responsive to an incoming trunk call for routing such call to an idle operator's position which has been rendered capable oi answering such a trunk call.

7. In a telephone system, a plurality of groups of trunk lines, a plurallty'of operators positions, means for marking each of said operators positions idle and selectable for use only when the operators at such positions are ready to receive incoming trunk calls, means for selectively conditioning certain of said positions in one manner to receive incoming trunk calls from only a limited number of said trunk groups, means for selectively conditioning other of said positions-in a difl'erent manner to receive incoming trunk calls from said limited number-oi tnmk groups, means for routing trunk callsfrom said limited number or groups to said certain operators positions in accordance with said firstv selective conditioning means in case any one or said ceruse; and means for routing trunk calls from said limited number of trunk ierent selective conditioning means only in case none of saidcertain operators positions are idle and selectable for use.

8. In a telephone system, a group oi incoming toll trunk lines,

tions idle and selectable for use only when the operators atsucn positions are ready to receive an incoming trunk call, means for selectively coriditioning only certain oi said operators positions groups to said other, operators positionsin accordance with said diia plurality or operators positions, means for marking each oi said operators posiadditional "distributor means eflective only in case none of said certain is idle and selectable for I calls from said trunk group to said certain operators positions in accordance with said one manner of selective conditioning means in case any one of said certain operators positions is idle an '1 selectable for use, and means for routing trunk calls from said trunk group to said other operators positions i accordance with said different manner of selec ive conditioning means only in case none of said certain operators positions are idle and selectable for use.

9; In a telephone system, a group of incoming toll trunk lines, a plurality of operators positions, means for marking each of said operators positions idle and selectable for use only when the operators at such positions are ready, to receive an incoming trunk call, means for selectively conditioning only certain of said operators positions in one manner to rec'eive incoming trunk calls from said trunk group, meansior selectively conditioning other of said operators positions in a. difierent manner to receive incoming trunk calls from said trunk group, and means for routing trunk calls from said trunk group to said other operators positions in accordance with said different selective conditioning means only in case none of said certain operators positions are idle and selectable for use.

10. In a telephone system, a plurality oi groups of incoming trunk lines, a plurality of operators positions, selective key means for each trunk group in each oi. said operators positions, each said selective key means having a normal and an operated position, each said selective key means in operated position preventing its operators position from receiving trunk calls from its corresponding trunk group and in normal position assigning its operator's position to repeive trunk calls from its corresponding trunk group. overflow selective key means for each trunk group in each of said operators positions, each said overflow selective key means having a normal position and an operated position, each said overflow selective key means in operated position preventing its operator's position from receiving trunk calls from its corresponding trunk group in case its corresponding selective key means is operated and each said overflow selective key means in normal position assigning its operator's position to rec'eive'trunk calls from its corresponding trunk group even though its corresponding selective key means is operated, and means for routing incoming trunk calls from said trunk groups to said operators positions .in accordance with the operated condition of said selective key means and in accordance with the operated condition obsaid overflow selective key means. 4 1

11. In a telephone system, a plurality of groups of incoming trunk lines, a plurality oi operators positions, selective key means for each trunk group in each of said operators positions, each said selective key means having a normal and in one manner to receive incoming trunk calls from said trunkgroup. means for selectively conditionihg otherof said operators positions in a different manner to receivsggcoming trunk calls from said-trunk groupiwdor routing trunk an operated position, each said selective key.

means in operatedposition preventing its operator's position from receiving trunk calls from its corresponding trunk group and ,in normal position assigning its operator's position to receive trunk calls from its corresponding trunk group, overflow selective key means for each trunk group in each 01. said operators positions, each said overflow selective key means having a normal position and an operated position, each said overflow selective key means in operated position preventing its operator's position from receiving trunk calls from its corresponding trunk group in case its corresponding selective key means is operated and each said overflow selective key means in normal position assigning its operators position to receive trunk.

calls from its corresponding trunk group even though its corresponding selective key, means is operated, means for marking each of said operators positions idle and selectable for use only when the operators at such positions are ready to receive an incoming trunk call, means for routing incoming trunk calls from said trunk groups to marked idle ones of said operators positions in accordance with the operated condition of saidselective key means, and means for routing incoming trunk calls from said trunk groups to marked idle ones of said operators positions in accordance with the operated condition of said overflow selective key means only in case none of the operators positions assigned for use on such trunk calls by said selective key means are idle and selectable.

12. Ina telephone system, a plurality of groups of incoming trunk lines, a plurality of operators desired ,ones 01' said. trunk groups, and means responsive to a trunk call in one of said trunk groups for operating the corresponding marking means at one of said operators positions which is assigned by only said overflow class of service keys to answer tEdfik calls from such a group.

15. In a telep one system, a group of trunk lines, an Opera r's position terminating said trunk lines, marking means in said operators position for marking said group of trunk lines in said position in response to a call in said trunk group, a class 01 service key for said trunk group at said operators position, means including said class of service key for controlling the operation of said marking means, an overflow class of service key for said trunk group at said operator's position, and means including said overflow class of service key for controlling the operation of said marking means independently of said class of] service key.

16. In a telephone system, an operators position, a trunk group terminating in said position,

positions, selective means for each trunk group in each of said operators positions, each said selective means operative to prevent its said position receiving trunk calls from its corresponding trunk groups, corresponding overflow selective means for each trunk group in each of said operators positions, each said corresponding overflow selective means capable of assigning its position to receive trunk calls from its correspondina trunk group when its corresponding selective means is operated, and means for routing incoming trunk calls from said trunk groups to said operators positions in accordance with said overflow key. in series with contacts on said overflow relay, means responsive to a trunk call in said group for operating said markingrelay over said first circuit in the event said first key is non-operated, and means responsive to a trunk call in said group for operating said marking relay over said second circuit only in the event said first key is operated to open said first circuit and said overflow key is rion operate'd.

14. In a telephone system, a plurality of operators positions, a plurality of trunk groups terminating in said operators positions, a marking means for each trunk group in each operator's -position, each marking means operative to mark its corresponding trunk group in its operator's position, a class of service key for each trunk group at each operator's position, said class of.

service keys at said operators positions operated by the operators thereat to selectively assign their positions to answer incoming. trunk calls from only desired'ones of said trunk groups, an overflow class or service key-for each trunk group at each operators position, said overflow class of service keys'at said positions operated by the operators thereat to selectively assign their positions to answer 'incon in atrunk calls from only a marking relay at said position individual to said trunk group for marking said trunk group at said position, a first circuit for said marking relay, a second circuit for said marking relay, means at said position for controlling the open or closed condition of said first circuit, other means at said position for controlling the open or closed condition of said second circuit, means responsive to a trunk call in said group for operating said marking relay over said first circuit in the event said first circuit is in closed condition under control of said first means, and means responsive to a trunk call in said group for operating said marking relay over said second circuit only in the event said first circuit is in open condition and said second circuit is in closed condition under control of said other means.

1'7. In a telephone system, an operator's position, a plurality of trunk groups terminating in said operator's position, a key for each trunk group at said operators position. said keys selectively operable by the operator thereat to assign her position to answer incoming trunk calls from only desired ones of said trunk groups, and an overflow key for each trunk group at said operator's position, said overflow keys also selectively operable by the operator thereat to assign her position to answer incoming trunk calls from only desired ones of said trunk groups and then only in the event the corresponding ones of said first mentioned keys have been operated by the operator at such positions.

18. In a telephone system, a plurality of operators positions. a group of trunk lines terminating in said positions, means for marking each of said positions idleand selectable for use only when the operators at such positions are ready to receive anincoming trunk call, means for selectively conditioning only certain of said operators positions to receive incoming trunk calls from said trunk group,a position distributor individual to said trunk group for distributing incoming trunk calls from said trunk group to said certain operators positionsin accordance with said selective conditioning means,-means in said distributor for sequentially assigning said certain positions if marked idle and selectable in a predetermined order and rotation for successive trunk calls from said trunk group, overflow means for selectively conditioning other of said operators positions to receive incoming trunk calls from said. trunk group, overflow distributor means in said distributor for distributing incoming trunk ators positions to receive incoming trunk calls from only a certain one of said trunk groups, a position distributor individual to said certain trunk group for selecting in a continuous cycle and in a predetermined order said certain operators positions which are available for use for successive incoming trunk calls from said certain trunlr group, other operators positions in which said plurality of trunk groups terminate, means for selectively conditioning only certain of said other operators positions to receive incoming trunk calls from only said certain trunk group,

said certain other operators positions which are available for use for incoming trunk calls from said certain trunk group, and said overflow means being eflective only in the event none or said first mentioned certain operators positions are available for use.

20. In a telephone system, a plurality of operators positions, a plurality of groups of trunk lines terminating in said positions, a position distributor individual to each trunk group, each distributor selecting in a continuous cycle and in a predetermined order said operators positions which are available for use for successive incoming trunk calls from its corresponding trunk group, other operators positions in which said plurality of trunk groups terminate, overflow means in each of said distributors, each said flrst mentioned plurality of operators positions are available for use.

22. In a telephone system, a plurality of operators positions, a group of trunk lines terminating in said positions, means for marking each oi said positions idle and selectable for use only when the operators at such positions are ready to receive an incoming trunk call, a position dis tributor for selecting in a continuous cycle and in a predetermined order said operators positions which are marked idle and selectable ior use for successive incoming trunk calls from said trunk group, other operators positions in which said group of trunk lines terminate, overflow means in said distributor for selecting said other operators positions for use for incoming trunk calls from, said trunk group, and said overflow means being effective only in the event none of said overflow means in said distributor for selecting first mentioned plurality 01' operators positions are idle and selectable for use.

23. In a telephone system,- a plurality of trunks. a plurality of operator positions, means for allotting calls received over said trunks to said operator positions, means at each 01 said positions effective when the operator thereat is busy handling a call allotted thereto for preventing additional calls from being allotted to said busy position, means at one of said positions for artificially busying said one position to prevent the allotment of calls thereto, and means includedin said allotting means for overriding the said artificial busy at said one position and extending a call overflow means selecting said other operators positions which are available for use for incoming trunk calls from its corresponding trunk group, and each of said overflow, means being effective only in the event none of said first men- I tioned plurality of operators positions are available for use.

21. In a telephone system, a. plurality of oper-.'

ators positions, a group of trunk lines terminating in said positions, a position distributor for selectingin a continuous cycle and in a predetermined order said operators positions which are available 'for ,use' fo successive incoming trunk calls from said trunk group, other operators in which said group of trunk lines ter- 'minate, overflow means in said distributor for' positions selecting said other operators positions which are'available' for use for incoming trunk calls from said trunk group, and said overflow means being effective only in the event none oi said thereto only in the event all of the remaining operator positions are busy.

24. In a telephone system, a plurality of operator positions, a distributor for distributing calls to said positions in a predetermined order, means for automatically busying positions to which calls have,been distributed by said distributor whereby subsequent calls are distributed to the remaining non-busy positions in a predetermined order, means operated at will at one of said positions for preventing said distributor from distributing calls thereto, and means including said distributor "for overriding said preventing means and distributing calls to said one position only in the event all of said remaining positions are busy.

25. In atelephone system, a plurality of operator positions, a distributor for distributing calls t said positions in a predetermined order, means for automatically busying positions to which calls have been distributed by said distributor whereby subsequent calls are distributed to the remaining non-busy positions in a predetermined order, means operated at will at one of said positions for preventing said distributor from distributing calls thereto, and means in said distributor effective when a call can not be distributed to any or said positions for overriding said, preventing- IMRE MOLNAR. 

